Question: Which of the following numbers is a factor of 96? ${4,5,9,11,13}$
Solution: By definition, a factor of a number will divide evenly into that number. We can start by dividing $96$ by each of our answer choices. $96 \div 4 = 24$ $96 \div 5 = 19\text{ R }1$ $96 \div 9 = 10\text{ R }6$ $96 \div 11 = 8\text{ R }8$ $96 \div 13 = 7\text{ R }5$ The only answer choice that divides into $96$ with no remainder is $4$ $ 24$ $4$ $96$ We can check our answer by looking at the prime factorization of both numbers. Notice that the prime factors of $4$ are contained within the prime factors of $96$ $96 = 2\times2\times2\times2\times2\times3 4 = 2\times2$ Therefore the only factor of $96$ out of our choices is $4$. We can say that $96$ is divisible by $4$.